1. Field of the Invention
The present invention relates to anhydrous fibrous magnesium oxysulfate and a process for the preparation thereof. This anhydrous fibrous magnesium oxysulfate may be suitably utilized as an additive for a resin, filler or filter medium, due to the fibrous structure thereof.
2. Description of the Related Art
Magnesium oxysulfates with different structures are known, and fibrous MgSO.sub.4.5Mg(OH).sub.2.3H.sub.2 O is already in use as a reinforcing material for resins, and the like. Further, MgSO.sub.4.5Mg(OH).sub.2.8H.sub.2 O also has a fibrous structure, and as a process for the preparation thereof, there is known a process for synthesizing same directly from magnesium oxide and magnesium sulfate. This process, however, is unsatisfactory in various aspects, such as conversion and production cost, when producing this compound on an industrial scale. These fibrous magnesium sulfates contain water of crystallization in the structures thereof, as apparent from the rational formulae thereof, but are dehydrated at a temperature of from 100.degree. to 300.degree. C., resulting in defective moldings when used for resins to be processed at a temperature exceeding this temperature range.